Decision support system for managing stormwater and greywater quality in informal settlements in South Africa

摘要

Managing the quality of stormwater and greywater in informal settlements are essential toudtheir growth. In this thesis, methodologies are developed for the assessment andudmanagement of stormwater and greywater quality based on the analysis of both nonstructuraludand structural control interventions.udThe objectives of the research were as follows:ud· Review stormwater runoff quality and treatment practices and the extent of runoffudand greywater management in rural and peri-urban areas of South Africa. Theudreview was to also determine the extent of quality control awareness andudexperience among stormwater management professionals and collate informationudupon which present and future needs can be assessed and addressed.ud· To develop a methodology to identify factors causing water quality managementudissues in low-cost, high-density settlements.ud· To develop a methodology to characterize storm and grey water quality as well asudsetting ambient water quality and management objectives.ud· To develop a methodology to identify and select potential non-structural andudstructural control interventions to manage storm and grey water quality.ud· Based on the above, to develop a decision support system for evaluation ofudpotential interventions for storm and grey water management at planning level.udThe methodologies used to achieve the above objectives consisted of: literature review;udconsultations with stakeholders; data analysis and computations; model development; andudmodel application.udThe current status of managing water quality pollution in urban areas is outlined and theudrelated problems, specifically those applicable to developing areas are discussed.udManagement interventions employed to date in the management of water quality effectsudare set out and the applicability of such interventions to developing areas is identified.udThe potential of expert systems is evaluated and the application of this system toudiiiudstormwater quality management models is assessed. A decision support system (DSS)udwas developed for rapid assessment of various water quality management interventions.udThe model is primarily targeted at those who are involved or are likely to be involved inudstormwater quality management including catchment managers, local governments orudmunicipalities, catchment management agencies, private consultants and researchers.udThe DSS and the related methodologies have been shown through Alexandra Townshipud(north of Johannesburg) case study, to be useful and to satisfy all the objectives set outudfor the research. The results of the research are summarised and the merits and limitationsudof the decision support systems are discussed. Recommendations for the direction ofudfuture research and the development of the existing model are detailed. Specifically, it isudrecommended that:ud· Extensive monitoring be undertaken in order to improve the defaults in the modelud· A research be undertaken into the extent to which GIS can be integrated to theudDSS to select appropriate management interventions and their sitesud· A research be undertaken into privatization and partnership in the ownership andudoperation of stormwater management systems.ud· Selection of least cost strategy with the DSS is presently achieved by trial anduderror process. The selection process can be improved if the DSS can be linked toudan optimizer.